Menu Choices

The MassGIS-Hydro menu currently has 6 menu choices available (7 when MassGIS Watershed Delineator extension is loaded): 

The "Display Watershed Analyst" menu choice

Application: Runs "DisplayWatershedAnalyst" script which will make the MassGIS Watershed Analyst tools and additional menu choices visible. After they are made visible, the first menu choice under the MassGIS-Hydro will be "Hide Watershed Analyst", which will enable the use to make these tools invisible again. 
Prerequisites: None 
User Action: User chooses the menu choice 
End Result: Tools and menu choices change 
Defaults: Default state of the project is that the Watershed Analyst tools and menus are invisible 
Notes:

The "Change Snap Tolerance For Finding Route" menu choice

Application: Runs "ChangeSnapRoute" script which will prompt user to enter new route snap tolerance in meters 
Prerequisites: None 
User Action: User chooses the menu choice and current snap tolerance is meters will be displayed. User may enter a new route tolerance in meters. Negative or non-number tolerances will not be accepted, although decimals will be accepted (i.e. 1.5)
End Result: A global variable will be reset to the new snap tolerance, which will be used when the user next uses a tool that locates a route (i.e. UpstreamTrace) 
Defaults: The initial, default snap tolerance is 30m. This is recommended except in rare cases when greater precision is necessary and a smaller tolerance is used (i.e. batch delineation for point events) 
Notes:

The "Display Event Table" menu choice

Application: Runs "DisplayEvents" script which will draw up point or linear events as themes in the view. 
Prerequisites: View window active 
User Action: User prompted to indicate type of event table (point or linear), and the name of the already-existing point or linear event table to display in the view. 
End Result: Point or linear event table will be displayed in the view in a default color. User can customize a legend for this theme, save it, and add the point or linear event to the themeinv.dbf table with its legend. If point or linear event tables are added to the themeinv.dbf table without a legend a default legend will be selected when the theme is added. Point or linear event tables added to the themeinv.dbf table will be available under the "A" button. 
Defaults:
Notes:

The "Make Point Event Table From Coverage or Shapefile" menu choice

Application: Runs "covToEventTable" script. 
Prerequisites: View window active, only 1 active river route theme in the view, point coverage or point shapefile active in the view
User Action: User prompted to name new point event table. User will be prompted to choose which .pat item in the coverage to use as a point event ID. Too large a snap tolerance will snap a point to multiple routes and a measure cannot be determined as a result. To small a snap tolerance will snap fewer than the ideal number of points to the route. 
End Result: A point event table will be created, named by the user. The number of points in the coverage that were not snapped to the route will be indicated. Graphic points will be created in the view for point events that were made. If the user is unsatisfied with the number of points snapped to the route, this menu choice can be used again with a different snap tolerance, and a new point event table created. User can also edit the point event table created by hand to add additional points that did not snap because they were farther away than the snap tolerance or too close to other routes. 
Defaults: Snap tolerance to route is 30m. Processing takes some time (i.e. 3 minutes for about 70 points). Add a status bar to indicate processing? 
Notes:

The "Make Linear Event Table From Point Event Table" menu choice

Application: Runs "PointToLinear" script, which creates a linear event table from a point event table. 
Prerequisites: Active view window, active centerline theme in View from the "A" button, active point event theme. 
User Action: If there are not 2 active themes - one a centerline and one a point event table, the user is warned and the script exits. If prerequisites are met, the user is prompted to name new linear event table. 
End Result: A linear event table will be created from a point event table by making a linear event from point to point, and from the last point to the mouth. 
Defaults:
Notes: Each linear event will have an id number from the eventid of the point event at its upstream end. The script works by taking each point event in the point event table and performing a downstream query on the point event table to find out which point events are downstream of the one point. Then, from that selected set downstream traces are performed and the distance from the mouth calculated. In this way the most upstream point that is downstream of the point in question is found, and the linear event is constructed between these 2 points 

The "Make Segmented Linear Event Table" menu choice

Application: Runs "SegmentedLinear" script, which creates a linear event table in 100m segments from an input linear event table. 
Prerequisites: Active view window. 
User Action: User prompted to name new linear event table. User prompted for linear event table to use. 
End Result: A linear event table will be created from an input linear event table. The new linear event table will have 100m linear events created from input linear events. If a linear event is not evenly divisible into 100m segments, the leftover segment is also made into a linear event. The output table's linear eventid is a "meta id" - multiple linear events can make up a meta linear event. 
Defaults:
Notes:

The "Change Snap Tolerance for Delineation" menu choice

Application: Runs "ChangeDelinSnap" script 
Prerequisites: In order to see this menu choice, the MassGIS Watershed Delineator extension must be loaded, and the View window must be active. 
User Action: User chooses the menu choice and current snap tolerance is meters will be displayed. User may enter a new route tolerance in meters. Negative or non-number tolerances will not be accepted, although decimals will be accepted (i.e. 1.5) 
End Result: A global variable will be reset to the new snap tolerance, which will be used when the user next uses a tool that delineates a watershed for point or line (not for poly - there is no snapping in that case). 
Defaults: The initial, default snap tolerance is 40m. This is recommended except in rare cases when greater precision is necessary and a smaller tolerance is used (i.e. batch delineation for point events) 
Notes:

Previous section: Buttons
Next section: Additional Notes
Back to Watershed Analyst Index

Last Updated 3/22/2000
EOEA Disclaimer | Privacy Policy